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Musculoskeletal Anatomy > Eyes & Ears > Flashcards

Eyes & Ears Flashcards

0
Q

What are the 2 parts of the fibrous coat?

A
  1. sclera

2. cornea

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1
Q

What are the three layers of the eyeball?

A
  1. fibrous coat (homologous to dura)
  2. vascular coat (homologous to arachnoid & pia)
  3. nervous coat (homologous to CNS)
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2
Q

What is the sclera?

A

-dense, white CT into which the extrinsic eye muscles insert

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3
Q

What is the cornea?

A
  • continuous with the sclera, but transparent to allow light to project to retina
  • most of the refraction of the light
  • avascular, draws nutrients from aqueous humor by diffusion
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4
Q

What are the constituents of the anterior, external eye?

A
  • eyebrow
  • superior palpebral sulcus
  • upper eyelid
  • pupil
  • caruncula lacrimalis
  • lateral angle of eye
  • medial angle of eye
  • bulbar conjunctiva
  • posterior border of eyelid
  • anterior border of eyelid
  • iris
  • lower eyelid
  • lateral palpebral commissure
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5
Q

What is conjunctiva?

A
  • conjunctiva is a thin, clear mucus membrane

- covers the anterior, external part of the eye & lines internal parts of both eyelids

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6
Q

What does the conjunctiva produce?

A

-conjunctiva + lacrimal gland produce fluid that bathes the anterior surface of the eye= keeps it moist & nourished

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7
Q

What is MALT?

A
  • mucosa-associated lymphatic tissue

- found w/in conjunctiva as well as immunoglobulins which it secretes

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8
Q

What does the vascular coat consist of?

A
  • blood vessels
  • choroid & structures
  • ciliary body which regulates the refraction of light
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9
Q

What is the choroid?

A

-layer of numerous anastamosing blood vessels

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10
Q

What does the ciliary body do?

A
  • controls the shape of the lens–> change refractory index

- helps with production of aqueous humor

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11
Q

What does the iris do?

A

controls pupil size

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12
Q

The iris has how many sets of muscles & what does each do?

A
  • 2 sets; control pupil size
    1. sphincter pupillae
    2. dilator pupillae
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13
Q

What is the sphincter pupillae innervated by?

A

-parasympathetic fibers from the Edinger-Westphal nucleus that travels along the oculomotor n. & decreases pupil size

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14
Q

What is the dilator pupillae innervated by?

A

-innervated by sympathetic nerves from the superior cervical ganglion & increases pupil size

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15
Q

What does the cornea cover? What is it innervated by? What are the parts which make it up?

A
  • iris, pupil & anterior chamber
  • accounts for 2/3 of eyes optical (refractory) power
  • sensory innervation by trigeminal nerve (CN V)
  • multilayered structure consisting of epithelium, collagen & endothelium
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16
Q

What makes up the lens? What about optical power? What happens with age?

A
  • composed of stiff elongated prismatic cells known as lens fibers
  • less optical power than cornea, but adjustable by ciliary muscles (accommodation- eyes change due to image coming close to face) (flex to make flat, relax to make round)
  • elasticity of the lens decreases with age= more difficult to focus on objects close to the eye (prebyopia)
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17
Q

What is in the anterior chamber?

A

-aqueous humor, ultrafiltrate of blood

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18
Q

What does the aqueous humor provide? Where does it come from? Where does it drain?

A
  • nutrition and assists in immune response
  • from ciliary body
  • drains through canal of Schlemm
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19
Q

What happens with an overproduction/underproduction of aqueous humor?

A

-can cause a build up of aqueous humor & increased P in the anterior chamber–> this is what happens in glaucoma & blindness results from damage to the optic n.

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20
Q

What does the nervous coat consist of?

A

-consists of retina

21
Q

What is the retina?

A
  • pigmented receptors & neurons that convey light information to ganglion cells
  • ganglion cells send axons centrally to the optic disc & forms the optic n.
22
Q

What is the retina? What does it contain?

A
  • multilayered inner lining of the eye
  • contains rods & cones, the photo-sensitive cells of the eye
  • highest density of cones are in the macula densa (macula lutea & fovea centralis)
23
Q

What are rods & cones? What do they respond to? What are they responsible for?

A
  • rods are more numerous than cones & more sensitive to light
  • rods do not respond to red light
  • cones detect color & provide acute vision; 3 types: red, blue, green
  • both rods & cones require protein retinal (metabolite of vit. A)
24
Q

The optic nerve/tract is an extension of what? What are its characteristics?

A

THE BRAIN

-is a CNS structure & should be a ‘tract’

25
Q

What surround the nerve & up to where?

A

meninges surrounds the nerve up to the sclera

26
Q

What two things extend to the lamina cribrosa?

A

subarachnoid space with CSF extends to lamina cribrosa

27
Q

Ganglion cells are like what?

A

-CNS neurons

28
Q

What are the two cells specific to the CNS for myelination?

A
  • oligodendrocytes myelinate the axons

- astrocytes surround cell bodies & dendrites

29
Q

What is papilledema?

A
  • one of 1st signs of increased intercranial P
  • increased CSF P limits venous return from retina & causes edema under optic disc
  • ophthalmoscopic view shows blurred disc margins where the optic disc is raised
30
Q

What is the vitreous body/humor?

A
  • clear, gel-like fluid
  • 98, 99% H2O
  • contains hyaluronic acid & type II collagen fibrils that are slowly replaced
  • sits up against retina, supporting the spherical shape of the globe & keeping the retina in place
31
Q

What is the hyaloid canal?

A
  • vestige of hyaloid artery used to nourish embryonic lens

- blood & cell debris removed by local phagocytes, but residual pieces of hyaloid artery remain as a type of floater

32
Q

What are floaters?

A
  • visual specks or clouds formed by tiny separated clumps of gel in the vitreous body that are too large to be phagocytized
  • born w/the # of floaters you will have
33
Q

How does retinal detachment occur?

A

-too little vitreous humor= doesn’t support eye= pulls away from retina

34
Q

What is the visual pathway? light transformed into what? by what? travel to where?

A
  • light hitting the retina is transformed into nerve impulses by the rods & cones
  • impulses travel through the optic n. to the optic chiasm
  • from optic chiasm, these signals travel to lateral geniculate body of the thalamus
  • after the lateral geniculate, signals travel through the optic radiations to the primary visual cortex of the occipital lobes
35
Q

What is the abducens n. responsible for innervating and what does that muscle do?

A

lateral rectus- abducts the eye (lateral gaze)

36
Q

What does the trochlear n. innervate? What does this muscle do?

A

superior oblique- internally rotates, depresses & abducts the eye (down & out)

37
Q

What does the oculomotor n. innervate?

A

inferior oblique, medial rectus, superior rectus & inferior rectus AS WELL as the ciliary body

38
Q

What are the 3 parts of the ear?

A

external, middle & inner ear

39
Q

What makes up the external ear? What are these structure for? What glands are there, what do they produce & what are they good for?

A
  • pinna (outer ear structure) & auditory meatus
  • these structures boost sound wave P & funnel it to the tympanic membrane
  • modified sebaceous glands line the external auditory meatus; create ear wax (cerumen)
  • ear wax protects the ear from irritation & infection
40
Q

Where is the middle ear (b/w what 2 structures)?

A
  • internal to tympanic membrane & external to oval window

- ossicles are w/in middle ear

41
Q

What are the 3 ossicles of the middle ear? What kind of joint?

A
  1. malleus: attaches to tympanic membrane distally & the incus proximally
  2. incus: connects the malleus to the stapes
  3. stapes: attaches to the oval window of the inner ear
    - articulations between ossicles are synovial joints
42
Q

Where does the auditory tube drain to?

A

middle ear into the nasopharynx

43
Q

What does the tensor tympani attach to? What does the stapedius attach to? What are they for?

A
  • tensor tympani to malleus
  • stapedius to the stapes
  • both contract to reduce movement of the ossicles & protect ear from excessive noise
44
Q

What are the parts of the inner ear? What is it innervated by?

A
  • cochlea, vestibule & semicircular canals

- innervated by vestibulococchlear n.

45
Q

What does the stapes do in relation to the cochlea?

A
  • movement of stapes at the oval window moves the perilymph (w/in the cochlea) in the scala vestibuli
  • this movement vibrates the endolymph in the scala media (cochlear duct), the basilar membrane & the Organ of Corti
  • movement of the hair cells of the Organ of Corti is converted to electric signals that travel along the vestibulocochlear n.
46
Q

What is the auditory pathway? What does it relay?

A
  • cochlear divison of the vestibulocochlear n. transmits n. impulses first back to its nucleus (the cochlear nucleus) then to the superior olivary nucleus
  • relays processed info; this processed info ascends to the inferior colliculus before being transmitted to the thalamus
  • from the thalamus this info is sent to the primary auditory cortex (in the temporal lobe)
47
Q

What system is responsible for balance?

A
  • vestibular system (equilibrioception)
  • visual system tells us where we are with respect to the external environment
  • P & proprioceptors, which tell us about position of our bodies
48
Q

What does the vestibule contain? What are these structures filled with/what do they have? What sits on top of the hair cells?

A
  • saccule, uricle & 3 semicircular canals
  • filled with fluid (endolymph)
  • all also have hair cells that when moved by gravity or motions of the head, generate n. impulses
  • otoliths (crystalline structures composed of gelatinous matrix & calcium carbonate) attach to the hair cell; amplify the effects of gravity or movement to activate the hair cells
49
Q

What are the semicircular canals made up of? What is at the base of each canal?

A
  • 3 hemicircular structures of bone, lined with periosteum & contain endolymph
  • horizontal, superior & posterior semicircular canals correspond roughly to the 3 planes of 3D space
  • at base of each canal is an enlargement (ampulla); as head and/or body moves, endolymph movement lags behind slightly, deforming the ampulla= hair cells in ampulla are affected by this movement which triggers n. impulses
50
Q

What is BPPV? What is it caused by?

A
  • Benign Paroxysmal Positional Vertigo: condition which the pt is overcome by a sudden sensation of spinning
  • thought to be due to disturbance of inner ear, in which otoliths from the saccule or utricle enter the semicircular canals & activate hair cells
  • diagnosis is based on pt history & Dix-Hallpike maneuver (the roll test)
  • treated with the Epley maneuver or Semont maneuver

Musculoskeletal Anatomy (9 decks)

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